The purpose of this project is the investigation of the mechanism of the reduction of proline to S-NH2 valeric acid in dental plaque from monkeys. Incubation of dental plaque homogenates with a variety of substrates suggests that proline reduction occurs via Stickland reactions involving other amino acids and also certain end products of glucose metabolism, particulary lactic acid. Following growth of a plaque sample in defined medium enriched with proline S-NH2 valeric acid production was associated with the growth in the culture of the amino acid utilizing organisms. The work is being directed towards elucidating the mechanism and products of these reactions and their contribution to the overall metabolism of dental plaque.